A number of openers for seeders or drills have been developed for single pass placement of separately delivered and spaced apart seed and fertilizer, a practice sometimes referred to as double shooting. This practice provides the obvious benefits of reduced fuel and labour usage and is also advantageous to those looking to reduce tillage. However, when using simultaneously depositing seed and fertilizer, whether liquid or granular (urea) or anhydrous ammonia (NH3) fertilizer, there is a concern in providing sufficient spacing between the deposited seed and fertilizer to avoid potentially damaging effects on the seed.
Prior art approaches to double shooting have typically been to use separate openers on the same drill or seeder to deliver the seed and fertilizer or to use openers having two or three outlets to side band the fertilizer alongside a single seed row or deposit fertilizer between a pair of seed rows. The use of two dedicated openers, for example in mid-row banding where a separate opener deposits fertilizer between two single shoot seed-depositing openers, is undesirable to those looking to keep tillage to a minimum, while in each of the single-opener side banding or paired row practices, the spacing between the seed and the fertilizer may not always be sufficient, as the fertilizer and seed outlets are in fairly close proximity. In side banding, the single seed outlet is typically found centrally on the opener with the fertilizer outlet being located slightly off to one side. In paired row applications, the two seed outlets are offset to opposite sides of the opener's central vertical plane, but the fertilizer is delivered between them at a central outlet. Delivery of the fertilizer to a depth somewhat below that of the seed has been applied in paired row applications to improve the separation, but this can cause unwanted disruption to the seed bed, potentially leading to inconsistency in seed placement and resulting emergence.